SOME RESULTS OF DEVELOPING MACHINES FOR CUTTING FROZEN SOIL BASED ON THE ETU-353 EXCAVATOR

O. L. LIPOV, N. G. BASOV, F. F. ZELINGER, V. G. YUDIN

At present, many different machines and attachments for cutting frozen soil have been developed in the country, with the aim of dividing it into blocks and subsequently excavating them in that form. In most cases, tractors are used as the base for such machines. However, of all these installations, those operate most successfully which combine cutting the soil with the movement of the machine. This, as a rule, is achieved by using mechanisms to reduce the travel speed of the tractor and devices for forced feed of the cutting member (bar). Thus, for example, in the bar-type installations of the trust “Tsentrospetsstroy” of Glavneftemontazh, the Permgiprogormash Institute, the trust “Transvodstroy” of the Ministry of Transport Construction of the USSR, Iskenderov and others, created on the basis of S-100 tractors, cylindrical gear speed reducers are used to reduce the travel speed. On the Tomsk Polytechnic Institute installation URMG-60, created on the basis of the swamp tractor TDT-60, a ratchet demultiplier is installed.

Machines equipped with speed reducers operate on the principle of continuous cutting of frozen soil and therefore provide 4–7 times greater productivity, a significantly lower energy consumption of the cutting process, and less specific tool wear than machines that do not have speed reducers. In this respect their advantages are indisputable.

However, the manufacture and installation of special speed reducers require additional expenditures and are not always accessible to production organizations. In this connection, attempts to create bar-type installations on multi-bucket trench excavators of the ETU-353 type deserve attention. These excavators have operating feed speeds and engine power that satisfy the working conditions of cutting-type working members in the development of frozen soils. Using the base of the ETU-353 excavator for the chassis of installations used in cutting frozen soil gives a significant economic effect, since the machine operates year-round (in winter most trench excavators stand idle, especially in the regions of Siberia).

The installations for cutting frozen soil based on the ETU-353 developed by other organizations have substantial disadvant—

because they do not have a device for forced penetration of the cutter bar and for holding it at the required depth. This considerably reduces the effectiveness of their use, since they cannot combine the process of cutting the soil with movement of the unit.

The Department of Mining Machines and Mine Transport of the Tomsk Polytechnic Institute developed a number of variants for re-equipping ETU-353 trench excavators for use in winter to cut frozen soil. Their distinguishing feature is the presence of forced penetration of the cutter bar by means of a hydraulic jack.

Below are presented the principal characteristics and a description of the designs of the units for cutting frozen soil developed and built at the department.

One of the proposed variants provides for installing on ETU-353 type excavators in winter the ordinary cutting sections of coal-cutting machines produced serially by our industry—cutter bars with the gearbox of the cutting section—with their drive taken directly from the excavator gearbox (Fig. 1).

Fig. 1. Schematic diagram of the unit for cutting frozen soil “Moroz”.

The re-equipment of the multi-bucket excavator consists of the following. With the onset of frosts, when operation of these machines in their standard configuration becomes impossible, the upper frame with the entire set of equipment is removed from them (the bucket working element, the turret shaft, the hopper, the conveyor, and other mechanisms). The removed equipment is repaired and preserved for the winter period. A removable mounted system, in the form of the cutting section of a KMP-type coal-cutting machine or of another type, is installed on the freed chassis. The gearbox of the cutting section of the coal-cutting machine 1 (Fig. 1) is attached to the rigid frame 2, which in turn is attached to the excavator frame 3. The cutting element is driven from the engine through the excavator gearbox 4 and the cardan shaft 5. The front end of the cardan shaft is attached to the shaft which, on the ETU-353 excavator, normally drives the conveyor.

To ensure the most rational operating modes of the chain-

some changes were made to the arrangement of the drive organ in the excavator gearbox; the necessity for these changes follows from the following circumstances.

The design of the cutting part of the KMP-type trenching machine is calculated so that the operating speed of the cutting chain is 2.12 m/sec at an engine-shaft rotational speed of 1465 rpm. The rotational speeds of the shaft driving the excavator belt conveyor, from which in our case power takeoff is provided by a cardan shaft to the cutting part of the KMP-type trenching machine, are insufficient, since they are only 260 or 456 rpm.

To obtain the required speeds of motion of the cutting chains, a pair of gears was replaced in the gearbox. As a result, the rotational speed of the conveyor drive shaft increased to 840 rpm. The intermediate shaft of the reducer was used as the primary shaft of the reducer of the cutting part of the KMP trenching machine, and the cardan shaft 5 was attached to it. As a result of all these changes, the chain of the bar installation operates at motion speeds of 2.1 m/sec and 1.07 m/sec, i.e., as in trenching machines.

This machine of the “Moroz” make can be used for broad study of cutting regimes for frozen soils with various physico-mechanical properties. For this purpose, between the speed gearbox of the ETU-353 excavator and the cutting part of the trenching machine, instead of the cardan shaft, a transfer case 6 and a speed gearbox 7 from the ZIL-164 automobile are installed (in Fig. 1 they are indicated by dashed lines). The latter serves to change the speeds of motion of the cutting chain and at the same time is a balancing dynamometer for measuring torque.

A second variety of mounted bar mechanism for cutting frozen soil on the ETU-353 excavator was also created; it was given the name BETU. This installation makes it possible to replace the ordinary equipment of the ETU-353 excavator with bar equipment at minimal cost.

In creating the second variant of the cutting equipment (Fig. 2), the authors generalized the experience of other organizations in re-equipping these excavators and took into account the results of work on the URMG-60 machine previously created at the department. In this case, when using the ETU-353 excavator base, only the bucket working organ with its boom is dismantled; it is preserved for the winter period. The head shaft, which drives the bucket chain, is installed during re-equipment in the lower position, at the base of the hopper frame. Instead of the drive sprockets of the bucket chain, the driving sprocket of the cutting chain of the trenching machine is fastened on the head shaft. At the base of the hopper frame 1 (Fig. 2), gussets 2 are welded on, to which the head-shaft brackets are attached. The head shaft with friction mechanism 3 is fastened in the brackets. The bar-mounting assembly is made in the form of a box of strip steel 30 mm thick. The box has three cells for attaching from one to three bars (accordingly, from one to three sprockets for driving the cutting chain are installed on the head shaft). The entire box is suspended from the head-shaft brackets by means of two lugs.

The gussets 2 do not interfere with the operation of the excavator in normal execution with the bucket chain, and at the same time such fastening makes it possible, with a bar length of 2.0 m, to cut a slot 1.3 m deep, since the bar can be set into the ground at an angle of 90° to the soil surface.

Setting the bar into the ground and lifting it are carried out by means of hydraulic jack 4, the cylinder of which is hinged to beam 5, welded--

made of two channels and fastened with bolts between the guides of the hopper frame 1, and the rod—to brackets 6 welded to the box in which the bar is mounted.

Fig. 2. Schematic diagram of the BETU installation for cutting frozen soil.

As in the preceding version of the installation for cutting frozen soil, the authors considered it expedient to have a cutting-chain speed on the order of \(2\ \mathrm{m/sec}\). In its standard design, the speed of rotation of the turas shaft does not provide the required speed of motion

Fig. 3. Kinematic diagram of the BETU installation for cutting frozen soil.

of the cutting chain of the bar. Therefore, in order to increase the cutting speed, the driving sprocket of the turas shaft with \(Z = 40\) and \(t = 50.8\ \mathrm{mm}\) was replaced by sprocket 1 (Fig. 3) with \(Z = 17\) and \(t = 50.8\ \mathrm{mm}\), as a result of which a cutting-chain speed of \(1.8\ \mathrm{m/sec}\) was obtained.

Transmission of rotation to the cutter-chain shaft 2 is effected from the excavator gearbox by a chain through a friction unit, which consists of sprocket 1, freely mounted on the hub of brake pulley 3. A disk is welded to the hub of sprocket 1; this disk is connected to the brake band that embraces pulley 3.

The presence of a friction mechanism in the transmission from the gearbox to the driving sprocket 4 protects the cutting chain from breakage when it encounters hard inclusions in the soil.

As already noted above, the installations for cutting frozen soil, designed and manufactured at the Department of Mining Machines and Mine Transport of the TPI, are equipped with a mechanism for forced feed of the bar. For this purpose, in the “Moroz” and BETU installations the ETU-353 excavator was additionally equipped with a hydraulic system, which includes: an oil pump with drive mechanism, a hydraulic distributor, an oil tank, a power cylinder, piping with connecting couplings, and high-pressure hoses. Oil pump 7 (Fig. 2), of the gear type, model NSh-40V, is fastened with bolts to the engine housing, similarly to the fastening on the DT-54A tractor. The pump drive shaft is rotated from the fan shaft, which in turn receives rotation from the engine distribution mechanism. Hydraulic distributor 8 is mounted on the right side of the excavator, in the tractor driver’s cab, by means of a bracket welded to the wall of the hopper. In both machine variants, three-spool hydraulic distributors of the R 40/75 model were used, operating well with the NSh-40V pump at low temperatures. Oil tank 9 is mounted inside the hopper.

Table

* With installation of the transfer case and gearbox from the ZIL-164.

In the installation of the first variant, setting and raising of the bar are performed by means of hydraulic jack 8 (Fig. 1) from the standard TDT-60 tractor. The working member is set when oil enters the lower (rod) cavity of the hydraulic jack. The hydraulic cylinder is hinged between two plates 9, rigidly fastened to the lower frame. The rod is hinged to the draw bracket 10, welded to the bar seat. When the rod is retracted, the motion is transmitted to bracket 10 through the bar seat 11, which is thereby driven into the ground.

In the second variant of re-equipment of the ETU-353 excavator,

(Fig. 2), the hydraulic system uses the main hydraulic cylinder from the E-153 “Belarus” excavator. The bar is driven in by feeding oil into the upper, rod-end chamber of the hydraulic jack.

Seamless high-pressure steel pipes, which have become widely used on tractors with mounted equipment, were used as oil lines. Flexible rubberized high-pressure hoses with cotton and metal braiding were laid from the hydraulic distributors to the hydraulic jacks.

The “Moroz” and BETU bar-type units showed good results (see table) when operating at enterprises in Tomsk, where they were used for cutting trenches, digging foundation pits, draining swamps, loosening soil in clay and sand quarries, and for winter replanting of trees.